Flavorings are used in foods in order to achieve taste impressions. In the sense of the present invention a flavoring is to be understood to be a single substance (flavoring) or a mixture of substances (flavorings) which have the organoleptic property or properties. These organoleptic properties include the characteristic of imparting a specific odor or taste to a mixture and the characteristic of giving rise to specific stimuli, which are transmitted via the trigeminus nerve and are thus detected.
Oils, such as, for example, vegetable oils and other triglycerides, which are used as solvents for the flavoring and themselves have a neutral odor and taste are not regarded as flavorings below.
If flavorings are to be ingested by a consumer in portions in the form of a liquid, the use of a capsule in which a core of a quantity of liquid containing flavoring is surrounded by a solid shell is an obvious measure. In this context the following problems and requirements, in particular, must be taken into consideration:    1. For optimum organoleptic detection, the release of the liquid core containing flavoring must already take place in the mouth. Appropriately it should be possible to consume the capsule including the shell, since separation of shell and liquid core is problematical after the capsule has been placed in the mouth.    2. Achieving a pleasant feeling in the mouth when consuming gelatin capsules is a technological challenge. In particular, hitherto it has been found to be disadvantageous that the majority of shells of ready-to-consume capsules available commercially are detectable as an unpleasant, rubbery, tough residue. Corresponding observations are made and found to be particularly negative especially in the case of large filled capsules (diameter θ 4 mm).    3. On consumption, a capsule shell in the mouth should preferably (a) not have a disturbing haptic effect (b) be easy to bite and (c) dissolve rapidly. The core liquid containing flavoring that is to be released or is released should give rise to a sensory effect with a substantial impact in the mouth.    4. At the same time, the capsule should be easy to handle, that is to say have a certain minimum size; in the case of spherical capsules in many cases a diameter θ of 4 mm is preferred.    5. In addition, for ease of handling during transport, storage and use the capsule should have an adequate temperature stability. In this context it is desirable that the capsules do not stick together even at temperatures above 30° C.
Spherical capsules having a liquid core and a solid shell surrounding this core are known and capsules having a diameter of more than 4 mm can, for example, be prepared by the rotary die method or, in the case of the capsules having a seamless shell, which are of particular interest, by a drip method using a multi-component nozzle (cf. Bauer, Frömming, Führer; Pharmazeutische Technologie; 1997). This method is also designated a multi-component nozzle method below. In this context (insofar as nothing different results from the context) references to the multi-component nozzle method are also to be understood as references to a multiplicity of related methods for the preparation of seamless capsules.
In the rotary die method capsules having a seam in the shell are produced via a punching method using rotary shaping rollers, in which method the capsule wall is made up and shaped from two gelatin halves that have been punched from a gelatin strip. For the preparation of soft gelatin capsules by the rotary die method stringent requirements are imposed in respect of the air conditioning. 20-30% relative atmospheric humidity at approximately 22° C. must be guaranteed in all production and packing areas.
In the multi-component nozzle method capsules having a seamless shell are prepared by a drip method. With this method a lipophilic core material and a hot gelatin solution are usually simultaneously pumped through a concentric multi-component nozzle so that they drip into a cold lipophilic cooling liquid, for example vegetable oil. With this method the nozzle can dip directly into the cooling liquid. When they drip in the capsules assume a ball shape (spherical shape) as a result of the surface tensions. As a result of the fall in temperature on contact with the cooling liquid, the gelatin-containing seamless capsule shell solidifies.
U.S. Pat. No. 4,481,157 and U.S. Pat. No. 4,251,195 describe methods and equipment for the continuous preparation of seamless capsules by the multi-component nozzle method where the nozzle dips into the cooling liquid.
JP 52-148635 describes a capsule having a diameter of 0.5-4 mm for immediate consumption. The wall thickness of the capsule is 50 μm-200 μm. A capsule diameter of more than 4 mm is not described.
However, a capsule diameter of 4 mm and more is required for better handling and portioning in the case of direct consumption and a strong flavoring impact by a single capsule in the mouth.
However, the larger a capsule the more difficult it is to achieve a thin, stable shell, since the stability of the capsule decreases substantially on drying and during transport as the capsule diameter/shell thickness ratio increases. Moreover, the centring of the core and the uniform enclosure of the core by a shell is extremely problematical in the case of large capsules.
U.S. Pat. No. 5,939,097 describes a food that contains capsules, which, in turn, contain a pharmaceutical active substance, the ratio of shell thickness to capsule diameter being 0.01-0.05 for capsule diameters of 0.5-5 mm. The capsules are intended to be incorporated in the food and are to be swallowed whole with the latter. The capsule is intended to release the core only in the gastrointestinal tract. The capsule shell contains gelatin or agar. No further details of the composition of the shell are given. Plasticizers are not mentioned.
U.S. Pat. No. 5,300,305 describes seamless capsules having a diameter of 2-9 mm, which are suitable for immediate consumption and are used to control bad breath. With these capsules, active substances for bad breath control are incorporated in the shell of the capsules on solubility grounds. The capsules are intended to remain in the mouth for a prolonged period so that the active substance influencing the bad breath is able to dissolve from the shell and give rise to a long-lasting effect in the mouth. The shell thickness is in the range of 30 μm to 2 mm. Illustrative embodiments show shell contents of not less than 13% (m/m) and only low plasticizer contents (sorbitol <10%, based on the shell). The capsule contains up to 25% (m/m) flavoring in the core, based on the total mass of the capsule. The capsules are, for example, prepared by a multi-component nozzle process.
The capsule shell was developed with a view to slow dissolution in the mouth and the Applicant's experiments have now shown that it proves to be rather hard and annoying when sucked. Accordingly, in particular the adverse sensation in the mouth, that is caused by the shell residues dissolving only slowly in the mouth, is a disadvantage when using the capsule described in U.S. Pat. No. 5,300,305 for an immediate, strong flavoring impression. Moreover, as has been mentioned, the flavoring content in the capsule is restricted to 25% and it is therefore not possible to achieve a strong flavoring impact.
U.S. Pat. No. 4,935,243 describes a soft gelatin capsule, the shell of which decomposes rapidly on chewing. The shell consists of water (15-30%), plasticizer (17.5-35%) and a small proportion of hydrated hydrolyzed starch (5-25%). Illustrative embodiments show shell solutions which have a solids content of approximately 75%.
A disadvantage is found to be in particular that, because of the high solids content and the resulting high viscosity, the shell formulations of U.S. Pat. No. 4,935,243 are suitable only for a rotary die method and not for a drip method, that is to say for the preparation of capsules with a seam, but not for the preparation of seamless capsules by, for example, the multi-component nozzle method.
WO 96/29986 describes seamless capsules having a diameter of 2-9 mm, which contain a pharmaceutical active substance against coughing. The capsule shells are 30 μm-500 μm thick and are intended to dissolve within 3.5-5 minutes. The capsule shells contain at least 10% water. A shell thickness to capsule diameter ratio is not given.
A disadvantage of the capsules according to WO 96/29986 is, in particular, the indicated slow rate of dissolution of the shell.
U.S. Pat. No. 5,620,707 describes seamless spherical capsules having a diameter of 2-15 mm and a shell thickness of 30 μm-2000 μm for use in drinks which contain flavoring, acesulfame and a further sweetener in specific proportions in the core. It can be seen from the illustrative embodiments that the shell contains more than 10% water and that sorbitol in amounts of more than 15% is used as plasticizer in the shell. A formulation with no plasticizer at all is also mentioned.